NTSB Factual Report

"THIS CASE WAS MODIFIED AUGUST 22, 2008."

On January 12, 2007, about 1230 eastern standard time, a float equipped Cessna 182Q, N502SS, registered to Sea & Air Sales LLC, experienced an engine compartment in-flight fire and loss of engine power, and was landed on a lake near Coral Springs, Florida. Visual meteorological conditions prevailed at the time and no flight plan was filed for the 14 Code of Federal Regulations (CFR) Part 91 personal flight from a lake located in Windermere, Florida, to Fort Lauderdale Executive Airport, Fort Lauderdale, Florida. The airplane was substantially damaged as a result of the in-flight and post landing fire, and the private-rated pilot, the sole occupant, was not injured. The flight originated about 1115 from Windermere, Florida.

The pilot stated that while en route, the engine "abruptly quit no bang just a sudden silence!" He advised the Fort Lauderdale Federal Aviation Administration (FAA) Control Tower, local controller, of the loss of engine power, declared a "mayday," and initiated an emergency descent for a forced landing on a lake. While descending, he observed fire and smoke coming from the engine compartment, and landed uneventfully on the lake. He turned off the electrical master switch, exited the cockpit, which was full of black acrid smoke and the stench of burning rubber and plastic, and stood on the left float while the airplane drifted to shore. He stepped onto land and the local fire department extinguished the fire. The airplane was recovered to a nearby airport for further examination.

Examination of the airplane revealed heat damage to the engine firewall, which compromised its strength, and also heat damage to structural members just aft of the firewall on the bottom of the fuselage. Heat damage was most extensive on the right side of the firewall, right exterior side of the engine compartment area, and aft of the firewall. A fire-sleeved, steel braided, flexible 10.00-inch (measured from flare to flare) fuel line, Teledyne Continental Motors (TCM) P/N 646644S4S10.00, Air Plains P/N 350-4-008.25, was fractured approximately 5 inches from the end of the B-nut at the engine-driven fuel pump. In addition, the fire sleeve in the fracture area had an oval area burned through the wall thickness of the fire sleeve. The burn hole area of the fire sleeve, and fracture point of the fuel line, were on the side of the fuel line adjacent to the firewall. The fuel line connected to a 90-degree downward oriented fitting located at the right side of the engine-driven fuel pump and also to a fitting at the top of the fuel control unit (FCU), and is a pressure return from the FCU to the engine-driven fuel pump.

An electrical cable (Cessna P/N 0770416PC6), which connects the external power receptacle located on the left lower side of the firewall, to the starter relay located on the upper right side of the firewall, exhibited localized damage (nearly completely fractured, missing insulation, and copper colored balls on the fractured ends of the cable) in the area of the damaged flexible fuel line. During removal of the electrical cable from the airplane, the cable broke in half. The gascolator drain cable was welded to the firewall in the area where the damaged flexible fuel line and electrical cable were noted. Attempts to separate the gascolator drain cable from the firewall resulted in pushing a hole in the firewall. A flexible fuel line, from the auxiliary fuel pump to the engine-driven fuel pump, was heat damaged and separated from the B-nut at the engine-driven fuel pump. The electrical cable and fractured flexible fuel line were marked at both ends, and submitted to the National Transportation Safety Board Materials Laboratory for further examination.

Examination of the electrical cable and flexible fuel line was performed by a Safety Board Fire and Explosion Specialist. The results of the examination of the electrical cable revealed two areas of damage that were consistent with electrical arching. Both areas exhibited beadings. Examination of the two pieces of the flexible fuel line revealed the ends of the steel braids on both sections were smooth and had a melted appearance with areas of pitting and erosion consistent with electrical arching. Additionally, orange-colored metallic material, some of which was spherical in shape and consistent in color with copper, was found on the ends of the braids on both sections.

The airplane was modified by an airframe and powerplant mechanic with inspection authorization (A&P/IA) on September 1, 2004, in accordance with (IAW) Supplemental Type Certificate (STC) SA00152WI. The STC removed the original carbureted O-470-U engine, and installed a TCM rebuilt fuel injected IO-550-D (27B) engine, which is approximately 3/4 inch longer than the original engine, and is equipped with an engine-driven fuel pump. The STC also required modification of the firewall. The rebuilt engine was supplied to the A&P/IA by the STC holder, and included the 10.00-inch fuel line as measured from flare to flare that was found fractured during the postaccident investigation. The airplane had accumulated approximately 371 hours since compliance with the STC.

The STC holder advised that the flexible, steel braided fuel line that was found fractured during the postaccident investigation was originally designed to be 8.25 inches in length as measured from flare to flare, but engines he receives from TCM are equipped with the same line being 10.00 inches in length as measured from the flare to flare. Review of pictures of an exemplar engine provided by TCM, showing the rear side of the engine with the installed 10.00-inch long fuel line, revealed it makes an approximate 300 degree change in direction to the right. As a result of the change in direction, the line has an outer radius that was calculated to be located just below the area where the accident airplane's fuel line was fractured and the fire sleeve was burned through.

Personnel from the FAA Aircraft Certification Office (ACO) located in Wichita, Kansas, stated that the ACO inspected a modified airplane before approving the STC. The ACO personnel added that the STC approval was also based on drawings submitted by the STC applicant, but the drawings were only required to depict modifications and not preexisting lines, hoses, etc.

Review of the maintenance records revealed the airplane was last inspected in accordance with an annual inspection on August 18, 2006; the airplane total time at that time was 2,946.5 hours. The airplane had accumulated 30.5 hours since the inspection at the time of the accident.

The A&P/IA mechanic who installed the engine in accordance with the STC reported that postaccident, he inspected five airplanes at his facility that had been modified per the STC. Of the five airplanes, two exhibited minor chafing of the electrical cable from the ground power unit receptacle, with the flexible fuel line from the auxiliary fuel pump, to the engine-driven fuel pump. One of the two airplanes had been modified by him, and the other airplane had been modified by the STC holder. He also stated that the area where the fractured fuel line was located was "tight."

NTSB Probable Cause

The improper design change associated with a Supplemental Type Certificate (STC), which resulted in an in-flight fire.